1. Field of Invention
The present disclosure of invention relates to a display apparatus and, more particularly, to a TFT substrate, a method of manufacturing the TFT substrate and a display apparatus having the TFT substrate.
2. Description of Related Technology
Recently, flat panel displays, such as organic light-emitting displays (OLED's), plasma display panels (PDP's) and liquid crystal displays (LCD's) have been developed as substitutes for heavy and large cathode ray tube (CRT) displays. A PDP displays images using plasma generated by electric discharges. An OLED displays images and characters using an organic electroluminescence property of a specific organic material and/or of a polymer. A LCD displays images by controlling the transmissivity of light passing through a liquid crystal layer.
In general, the LCD includes a thin-film transistors (TFT) supporting substrate, a common electrode supporting substrate spaced apart from the TFT substrate and a liquid crystal layer disposed between the TFT substrate and the common electrode substrate. If the TFT substrate and the common electrode substrate become misaligned relative to one another during a mass production manufacturing process, the display quality of the LCD can be adversely affected.
In order to prevent display quality from being significantly affected adversely by substrate-to-substrate misalignment, a color filter on array (COA) structure has been proposed in which color filters that are normally on the common electrode substrate are instead disposed on the TFT substrate. However, if the COA structure is used, impurities from the color filters may elute through gaps or openings between pixel electrodes and contaminate the liquid crystal layer thereby causing undesirable afterimages to be displayed.
Furthermore, when an organic insulating layer is used as a planarization layer under the pixel electrode, impurities from the organic insulating layer may elute into the liquid crystal layer. As a result, the liquid crystal is also contaminated, and the afterimage problem increases.